Sorry Craig, I missed this going by. That particular block has 2µm tick marks, but can definitely be used at 1µm by going between the marks. I suspect it came off a Nikon Labophot, but it was already cut off when I bought it.
Some newer Nikon blocks have 1µm marks. I also have one of those. The appearance seems to differ in a predictive way, at least from my samples--the older 2µm blocks have a coarse focus wheel with big, bumpy knurling; the newer 1µm blocks have a coarse focus wheel with smaller, uniformly-ridged knurling. There may be exceptions--this is only my experience. To see one of each, compare the second and third pictures in this post
Also, Dunksargent posted nice images of the older style Nikon block in this thread
Both the the new and old style Nikon blocks work really well in my experience, and I happily use either. The Olympus BHMJ that I use for subject positioning is also very good, and could easily handle use as the stacking movement, as others have shown. I have a few more of these Olympus blocks in the basement, slated for various projects I have in mind.
My Newport 462 linear stage does not perform remotely at the level pf any of my microscope focus blocks. Backlash, stiction, smoothness, lack of ability to switch between coarse and fine movement--there are many reasons I prefer focus blocks for stacking. If this linear stage is representative--and it may not be--my sense is that they are useful for pre-shooting positioning of subject or camera, but strongly suboptimal for providing stacking movement. But there are a wide range of linear stages, and I have no idea how most of them behave.
Ab, wonderful images! You did yourself proud, here.
As to those who prefer to crank by hand, this must be serious different- strokes-for-different-folks territory. Cool that there are people who find a kind of zen in it--but for me, it would be brutal drudgery. With automation, I love the fact that I can spend my time on thinking about what to show, how to show it, what to do with light, etc.--and then walk away and let the machine do the repetitive chores. I can PP a stack while the machine is shooting another. For me, a high-mag macro rig is a question-answering machine, in that it sees in ways that have never been seen before; I'd rather be thinking about new questions, and pondering over answers that inevitably lead to more questions, than sitting in the dark turning a knob 1500 times.